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  • Best system for creating a 2d racing track

    - by tesselode
    I am working a 2D racing game and I'm trying to figure out what is the best way to define the track. At the very least, I need to be able to create a closed circuit with any amount of turns at any angle, and I need vehicles to collide with the edges of the track. I also want the following things to be true if possible (but they are optional): The code is simple and free of funky workarounds and extras I can define all of the parts of the track (such as turns) relative to the previous parts I can predict the exact position of the road at a certain point (that way I can easily and cleanly make closed circuits) Here are my options: Use a set of points. This is my current system. I have a set of turns and width changes that the track is supposed to make over time. I have a point which I transform according to these instructions, and I place a point every 5 steps or so, depending on how precise I want the track to be. These points make up the track. The main problem with this is the discrepancy between the collisions and the way the track is drawn. I won't get into too much detail, but the picture below shows what is happening (although it is exaggerated a bit). The blue lines are what is drawn, the red lines are what the vehicle collides with. I could work around this, but I'd rather avoid funky workaround code. Beizer curves. These seem cool, but my first impression of them is that they'll be a little daunting to learn and are probably too complicated for my needs. Some other kind of curve? I have heard of some other kinds of curves; maybe those are more applicable. Use Box2D or another physics engine. Instead of defining the center of the track, I could use a physics engine to define shapes that make up the road. The downside to this, however, is that I have to put in a little more work to place the checkpoints. Something completely different. Basically, what is the simplest system for generating a race track that would allow me to create closed circuits cleanly, handle collisions, and not have a ton of weird code?

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  • Dual Xeon Server voltages are low

    - by Mindflux
    I've got a whitebox server running CentOS 5.7. It's a Dual Xeon 5620, 24GB of RAM. The mainboard is a SuperMicro X8DT6-F and the chassis is a SC825TQ-R720LPB. Dual 720W Power supplies. We had a big power outage a couple weeks back that took down everything, I don't have any pre-power outage figures for this server, and the only reason I noticed these is because when I was bringing up the servers I was checking them out with more scrutiny than usual. http://i.imgur.com/rSjiw.png (Image of voltage readings) As you can see, CPU1 DIMM is low, +3.3V is high, 3.3VSB is high, +5v is high, +12v is REAL LOW (out of normal 5% (plus/minus))... and VBAT is off the charts. With my whitebox VAR we've tried the following: Swap out PSU with another server I have with the same PSUs. Try different power cord Update BMC/IPMI firmware in case readings were wrong (They aren't) Update BIOS Try different PDU Try a different outlet and/or circuit Replaced Voltage Regulator Unit At this point, the only thing we haven't done, seemingly is replace the mainboard.. which is what the next step will be unless something else shines some light on the situation. I should mention the system is rock solid otherwise which is a surprise given the 12v voltage is that far off.

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  • Skype Connect as SIP/Trunk for Asterisk

    - by Kaurin
    First off: I'm not sure if this should be on superuser or here. I have recently built a few Asterisk boxes with OpenVOX FXO/FXS ports little or no trouble. My current project is building an Asterisk box with SIP trunks. My current employer insisted on getting Skype Business/Skype connect for that purpose. After reviewing the Skype Connect plan, I agreed, because I thought it is going to be straightforward: Purchase G729 licences and setup SIP trunk/trunks. Boy was i wrong :) Here is the setup: The setup is for calling US numbers only via skype (we got skype US minute bundles in skype connect) AsteriskNOW - Asterisk 1.4 + asterisk-gui Trunks: SIP Trunk configured with Skype Connect - shows as registered Users: 2 test extensions. Both work fine when calling each other, voicemail etc works fine too The asterisk box is behind a Mikrotik router which i configured to forward all relevant ports: 5060-5090 UDP, 10000-20000 UDP. When trying out an extension outside of my LAN, it worked. I could make calls to the other extension. Outgoing rule: _NXXXXXXXXX Strip:0 Prepend:+1 Use skype trunk Inbound rule: Trunk: Skype Pattern: s Destination: Extension1 (6210) Here is the output of asterisk CLI (-rvvvvv) with outgoing calls: http://pastebin.com/eWVpL72e you can see the circuit-busy response when using trunk1 (skype) When calling my Skype Connect number from the outside, I get nothing in the logs. Can anyone with Skype Connect / Asterisk experience help out? :)

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  • Routing a single request through multiple nginx backend apps

    - by Jonathan Oliver
    I wanted to get an idea if anything like the following scenario was possible: Nginx handles a request and routes it to some kind of authentication application where cookies and/or other kinds of security identifiers are interpreted and verified. The app perhaps makes a few additions to the request (appending authenticated headers). Failing authentication returns an HTTP 401. Nginx then takes the request and routes it through an authorization application which determines, based upon identity and the HTTP verb (put, delete, get, etc.) and URL in question, whether the actor/agent/user has permission to performed the intended action. Perhaps the authorization application modifies the request somewhat by appending another header, for example. Failing authorization returns 403. (Wash, rinse, repeat the proxy pattern for any number of services that want to participate in the request in some fashion.) Finally, Nginx routes the request into the actual application code where the request is inspected and the requested operations are executed according to the URL in question and where the identity of the user can be captured and understood by the application by looking at the altered HTTP request. Ideally, Nginx could do this natively or with a plugin. Any ideas? The alternative that I've considered is having Nginx hand off the initial request to the authentication application and then have this application proxy the request back through to Nginx (whether on the same box or another box). I know there are a number of applications frameworks (Django, RoR, etc.) that can do a lot of this stuff "in process", but I was trying to make things a little more generic and self contained where different applications could "hook" the HTTP pipeline of Nginx and then participate in, short circuit, and even modify the request accordingly. If Nginx can't do this, is anyone aware of other web servers that will perform in the manner described above?

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  • My desktop has started overheating -- how hot is hot?

    - by Jerry
    I have a two year old desktop, some random quad core HP desktop. It used to run very quietly, but in the past month, the fans start up anytime anything "serious" is being done -- compiles, playing video, etc. Right now, speedfan and speccy report the cores are between 50C and 70C. Speedfan reports this as hot. (Nice flame icon.) Well, the system does sit on my carpet, so two weeks ago, I took off the lid, and cough *cough* it was pretty filled with dust. I got out an air can, turned on a vacuum and carefully got out all the dust that I saw on the CPU fan the case fans any fan I saw (graphics board) and blew out all the dust I could from all the circuit boards. And then I closed the case back up. It has definitely run cooler since then, but it still runs hot, and I hear high speed fan noise I never heard before. How hot is too hot? At what temps do consumer grade CPUs die? What should I be looking to do? Replace CPU fan? (It seems to work) Replace power supply fan? Assuming the dust problem is gone, where should I be looking to determine why the machine is heating up? Epilogue: After following the various pieces of advice given here, the system did run cooler, but it was still noticeably running louder (hotter) than just a few months prior. I ended up purchasing a new cpu heatsink and fan and during installation found the cooling grease from the original heatsink was just a dried, cracked layer, probably more of an insulator than heat transfer agent. With the new fan AND the new heatsink compound, the system ran much much cooler and the fan rarely turns on.

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  • Windows XP Boot Issue - Diagnosing A Hard Drive Failure

    - by duffymo
    My five-year-old HP desktop running Windows XP SP3 wouldn't boot from the hard drive yesterday afternoon. I would see the boot sequence begin, then nothing but a black screen. Fortunately, I had just done an Acronis backup to my external drive in the morning, and I have a bootable USB key. I put the USB key into the drive, powered up the machine, and put the USB key first in line in the boot sequence. Voila! My machine came alive. But now I'm confused as to what the problem is and what to do next. I assumed that my hard drive was toast. But now that the machine is alive I can see files on my C: drive that have changes I made just yesterday. Clearly the drive is not dead. Here are my questions: What could explain my inability to boot from the hard drive? What would a remedy be? What's my best course of action? Should I replace the hard drive with a new one? If I replace the hard drive, do I reinstall the OS and apply the backup I did yesterday? If I decide that re-installing Windows XP makes no sense, how do I get back the Acronis backup that I did yesterday? I don't want to lose that. UPDATE: I just learned one more key fact. I'm having some work done on my house. I neglected to shut my machine down before the contractor came. My wife said he shut down the power to do some work on a circuit and then powered the house back up. I have a surge protector, but is it possible that cycling the power did some damage?

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  • What does this diagnostic output mean?

    - by ChrisF
    I recently had a fault with my broadband connection. It turned out to be a fault with the ISP's or teleco's equipment. My ISP posted this diagnostic, but while I understand it in general, I'd like to to know more about the details. I'm assuming that ATM means Asynchronous Transfer Mode and PPP means Point to Point Protocol. It was this that my router was indicating as the fault. xDSL Status Test Summary Sync Status: Circuit In Sync General Information NTE Status: NTE Power Status: Unknown Bypass Status: Upstream DSL Link Information Downstream DSL Link Information Loop Loss: 9.0 17.0 SNR Margin: 25 15 Errored Seconds: 0 0 HEC Errors: 0 Cell Count: 0 0 Speed: 448 8128 TAM Status: Successfully executed operation Network Test: Sub-Test Results Layer Name Value Status Modem pass Transmitter Power (Upstream) 12.4 dBm Transmitter Power (Downstream) 8.8 dBm Upstream psd -38 dBm/Hz Downstream psd -51 dBm/Hz DSL pass Equipment Vendor Name TSTC Equipment Vendor Id n/a Equipment Vendor Revision n/a Training Time 8 s Num Syncs 1 Upstream bit rate 448 kbps Downstream bit rate 8128 kbps Upstream maximum bit rate 1108 kbps Downstream maximum bit rate 11744 kbps Upstream Attenuation 3.5 dB Downstream Attenuation 0.0 dB Upstream Noise Margin 20.0 dB Downstream Noise Margin 19.0 dB Local CRC Errors 0 Remote CRC Errors 0 Up Data Path interleaved Down Data Path interleaved Standard Used G_DMT INP INP Upstream Symbols n/a INP Upstream Delay 4 ms INP Upstream Depth 4 INP Downstream Symbols n/a INP Downstream Delay 5 ms INP Downstream Depth 32 ATM Reason: No ATM cells received fail Number of cells transmitted 30 Number of cells received 0 number of Near end HEC errors 0 number of Far end HEC errors n/a PPP Reason: No response from peer fail PAP authentication nottested CHAP authentication nottested (I'm not sure that Super User is the best place to ask this, but two people have suggested I ask it here so here I am).

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  • Is it possible for a faulty processor to cause audio static/noise?

    - by Tom
    I have a Core 2 Extreme processor I received from a friend and have set up an XBMC box using it. However, I constantly get audio static whenever playing any music or videos. Here is a video of the sound: http://www.youtube.com/watch?v=SqKQkxYRVA4 I have tried replacing everything short of the case and the processor, including cables, audio interfaces, operating systems, ram, etc, leading me to think it might be either the case shorting out the motherboards I have tried or a faulty processor. Is it possible for a faulty processor to cause audio static/noise? Any feedback would be appreciated. Edit - Here's a list of things I have tried: Reinstalling OS Installing/upgrading/repairing PulseAudio/Alsa Installing alternate OSes, straight Ubuntu, Lubuntu, Xubuntu, Arch, Mint, Windows 7 Switching audio from the external card to internal Optical, audio out through HDMI, audio out through headphones Different ports on receiver (my main desktop sounds fine on the same sound system) Different optical cables Unplugging everything unnecessary from the motherboard (1 HD, 1 Stick of Ram, 1 Keyboard) Swapping out ram Swapping out the motherboard Replacing the Graphics Card (was replaced due to fan being noisy, not specifically for this problem) Different harddrives Swapping power supply Disabling onboard audio Switching Power Cable Plugging in through surge protector Plugging into different outlet on separate circuit

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  • Why do manufacturers not show all hardware power usage?

    - by Drew
    I find it slightly more difficult to build a computer when I do not know how much power is needed for a component. When selecting a power supply for a computer, it is difficult to know how large of one to get. You don't want to go too large for cost reasons and circuit reasons, but you don't want to go too low and not be able to properly use every component. For instance, a graphics card might say "Minimum of a 500 Watt power supply. (Minimum recommended power supply with +12 Volt current rating of 30 Amps.)" But it really needs 360W (12V * 30A). So why don't they just say "Uses 360W max and xxxW peak"? Processors, I have noticed are good at reporting their power usage, but aside from processors and sometimes graphics cards, power usage is easily found. What is the power consumed by the Blu-ray / DVD drives? By the HDDs/SSDs? By the Mobo? etc. Why are these questions not easily answered when building a machine?

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  • VMware "boot screen" - add info like contact, phone number, etc.?

    - by TheCleaner
    I've tried searching Google and VMware's KB but maybe I'm not typing the right search criteria...only finding ways to fix problems with booting or screen issues. On the default boot screen of a host it looks similar to this picture from GIS: I'm curious if it is possible somehow to make it look like this instead (adding custom details): I know for the most part the info is "useless" since it is administered remotely, etc. But when I deploy standalone hosts to branch offices, it'd be nice for them to see this type of info on the boot screen. I may also include the VMs hosted on it (again on standalone hosts). Normal monitoring, etc. will be done remotely. This is strictly for odd times when the branch contact may say "the electricians are saying they need to turn off this circuit but I have no idea who to call in IT to tell them this box needs to be shut down" or similar. Anyone who has dealt with small branch offices can tell you that if it isn't labeled they easily forget what it is for and will simply say after the incident "I didn't know what it was or who to call." Possible?

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  • Why does pulling the power cord then pressing the power button fix a non-booting PC?

    - by sidewaysmilk
    I've been working at this institution for about 6 years. One thing thing that I've always found curious is that sometimes—especially after a power outage—we find a PC that won't boot when the power button is pressed. Usually, the fans will spin up, but it won't POST. Our solution is to pull the power cord, press the power button with the computer unplugged, then plug it in and turn it on. It seems more common with Gateway brand PCs than the Dells or HPs that we have around. Does anybody know what pressing the power button does when the computer is unplugged? I have some vague notion that closing the power button circuit allows some capacitors to discharge or something, but I'd like a firmer answer to offer my users when they ask me what I'm doing. My best guess as to why fans can spin but it can't POST is that the BIOS is in some non-functional state. I don't know how BIOS stores state, but my best guess is that there is some residual garbage in its registers or something, like the stack pointer isn't starting at 0 maybe?

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  • Three Key Tenets of Optimal Social Collaboration

    - by kellsey.ruppel
    Today's blog post comes to us from John Bruswick! This post is an abridged version of John’s white paper in which he discusses three principals to optimize social collaboration within an enterprise.   By [email protected], Oracle Principal Sales Consultant Effective social collaboration is actionable, deeply contextual and inherently derives its value from business entities outside of itself. How does an organization begin the journey from traditional, siloed collaboration to natural, business entity based social collaboration? Successful enablement of enterprise social collaboration requires that organizations embrace the following tenets and understand that traditional collaborative functionality has inherent limits - it is innovation and integration in accordance with the following tenets that will provide net-new efficiency benefits. Key Tenets of Optimal Social Collaboration Leverage a Ubiquitous Social Fabric - Collaborative activities should be supported through a ubiquitous social fabric, providing a personalized experience, broadcasting key business events and connecting people and business processes.  This supports education of participants working in and around a specific business entity that will benefit from an implicit capture of tacit knowledge and provide continuity between participants.  In the absence of this ubiquitous platform activities can still occur but are essentially siloed causing frequent duplication of effort across similar tasks, with critical tacit knowledge eluding capture. Supply Continuous Context to Support Decision Making and Problem Solving - People generally engage in collaborative behavior to obtain a decision or the resolution for a specific issue.  The time to achieve resolution is referred to as "Solve Time".  Users have traditionally been forced to switch or "alt-tab" between business systems and synthesize their own context across disparate systems and processes.  The constant loss of context forces end users to exert a large amount of effort that could be spent on higher value problem solving. Extend the Collaborative Lifecycle into Back Office - Beyond the solve time from decision making efforts, additional time is expended formalizing the resolution that was generated from collaboration in a system of record.  Extending collaboration to result in the capture of an explicit decision maximizes efficiencies, creating a closed circuit for a particular thread.  This type of structured action may exist today within your organization's customer support system around opening, solving and closing support issues, but generally does not extend to Sales focused collaborative activities. Excelling in the Unstructured Future We will always have to deal with unstructured collaborative processes within our organizations.  Regardless of the participants and nature of the collaborate process, two things are certain – the origination and end points are generally known and relate to a business entity, perhaps a customer, opportunity, order, shipping location, product or otherwise. Imagine the benefits if an organization's key business systems supported a social fabric, provided continuous context and extended the lifecycle around the collaborative decision making to include output into back office systems of record.   The technical hurdle to embracing optimal social collaboration would fall away, leaving the company with an opportunity to focus on and refine how processes were approached.  Time and resources previously required could then be reallocated to focusing on innovation to support competitive differentiation unique to your business. How can you achieve optimal social collaboration? Oracle Social Network enables business users to collaborate with each other using a broad range of collaboration styles and integrates data from a variety of sources and business applications -- allowing you to achieve optimal social collaboration. Looking to learn more? Read John's white paper, where he discusses in further detail the three principals to optimize social collaboration within an enterprise. 

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  • Silverlight Cream for December 07, 2010 -- #1004

    - by Dave Campbell
    In this Issue: András Velvárt, Kunal Chowdhury(-2-), AvraShow, Gill Cleeren, Ian T. Lackey, Richard Waddell, Joe McBride, Michael Crump, Xpert360, keyboardP, and Pete Vickers(-2-). Above the Fold: Silverlight: "Grouping Records in Silverlight DataGrid using PagedCollectionView" Kunal Chowdhury WP7: "Phone 7 Back Button and the ListPicker control" Ian T. Lackey Shoutouts: Colin Eberhardt has some Silverlight 5 Adoption Predictions you may want to check out. Michael Crump has a post up showing lots of the goodness of Silverlight 5 from the Firestarter... screenshots, code snippets, etc: Silverlight 5 – What’s New? (Including Screenshots & Code Snippets) Kunal Chowdhury has a pretty complete Silverlight 5 feature set from the Firestarter and an embedded copy of Scott Guthrie's kenote running on the page: New Features Announced for Silverlight 5 Beta From SilverlightCream.com: Just how productive is WP7 development compared to iOS, Android and mobile Web? András Velvárt blogged about a contest he took part in to build a WP7 app in 1-1/2 hours without any prior knowledge of it's funtion. He and his team-mate were pitted against other teams on Android, IOS, and mobile Web... guess who got (almost) their entire app running? ... just too cool Andras! ... Grouping Records in Silverlight DataGrid using PagedCollectionView Kunal Chowdhury has a couple good posts up, this first one is on using the PagedCollectionView to group the records in a DataGrid... code included. Filtering Records in Silverlight DataGrid using PagedCollectionView Kunal Chowdhury then continues with another post on the PagedCollectionView only this time is showing how to do some filtering. DeepZoom Tips and Techniques AvraShow has a post up discussing using DeepZoom to explore, in his case, a Printed Circuit Board, with information about how he proceeded in doing that, and some tips and techniques along the way. The validation story in Silverlight (Part 2) Gill Cleeren has Part 2 of his Silverlight Validation series up at SilverlightShow. This post gets into IDataErrorInfo and INotifyDataErrorInfo. Lots of code and the example is available for download. Phone 7 Back Button and the ListPicker control Ian T. Lackey has a post up about the WP7 backbutton and what can get a failure from the Marketplace in that area, and how that applies to the ListPicker as well. Very Simple Example of ICommand CanExecute Method and CanExecuteChanged Event Richard Waddell has a nice detailed tutorial on ICommand and dealing with CanExecute... lots of Blend love in this post. Providing an Alternating Background Color for an ItemsControl Joe McBride has a post up discussing putting an alternating background color on an ItemsControl... you know, how you do on a grid... interesting idea, and all the code... Pimp my Silverlight Firestarter Michael Crump has a great Firestarter post up ... where and how to get the videos, the labs... a good Firestarter resource for sure. Adventures with PivotViewer Part 7: Slider control Xpert360 has part 7 of the PivotViewer series they're doing up. This time they're demonstrating taking programmatic control of the Zoom slider. Creating Transparent Lockscreen Wallpapers for WP7 I don't know keyboardP's name, but he's got a cool post up about getting an image up for the WP7 lock screen that has transparent regions on it... pretty cool actually. Windows Phone 7 Linq to XML 'strangeness' Pete Vickers has a post up describing a problem he found with Linq to XML on WP7. He even has a demo app that has the problem, and the fix... and it's all downloadable. Windows Phone 7 multi-line radio buttons Pete Vickers has another quick post up on radio buttons with so much text that it needs wrapping ... this is for WP7, but applies to Silverlight in general. Stay in the 'Light! Twitter SilverlightNews | Twitter WynApse | WynApse.com | Tagged Posts | SilverlightCream Join me @ SilverlightCream | Phoenix Silverlight User Group Technorati Tags: Silverlight    Silverlight 3    Silverlight 4    Windows Phone MIX10

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  • Joy! | Important Information About Your iPad 3G

    - by Jeff Julian
    Looks like I was one of the lucky 114,000 who AT&T lost their email to “hackers”.  Why is “hackers” in “double quotes”.  I can just imagine some executive at AT&T in their “Oh No, We Messed Up Meeting” saying, what happened?  Then someone replied, well we have had a breach and “hackers” broke in (using the quote in the air gesture) and stole our iPad 3G customers emails. Oh well, I am sure my email has been sold and sold again by many different vendors, why not AT&T now.  At least Dorothy Attwood could have gave us her email to give to someone else instead of blinking it through a newsletter system. June 13, 2010 Dear Valued AT&T Customer, Recently there was an issue that affected some of our customers with AT&T 3G service for iPad resulting in the release of their customer email addresses. I am writing to let you know that no other information was exposed and the matter has been resolved.  We apologize for the incident and any inconvenience it may have caused. Rest assured, you can continue to use your AT&T 3G service on your iPad with confidence. Here’s some additional detail: On June 7 we learned that unauthorized computer “hackers” maliciously exploited a function designed to make your iPad log-in process faster by pre-populating an AT&T authentication page with the email address you used to register your iPad for 3G service.  The self-described hackers wrote software code to randomly generate numbers that mimicked serial numbers of the AT&T SIM card for iPad – called the integrated circuit card identification (ICC-ID) – and repeatedly queried an AT&T web address.   When a number generated by the hackers matched an actual ICC-ID, the authentication page log-in screen was returned to the hackers with the email address associated with the ICC-ID already populated on the log-in screen. The hackers deliberately went to great efforts with a random program to extract possible ICC-IDs and capture customer email addresses.  They then put together a list of these emails and distributed it for their own publicity. As soon as we became aware of this situation, we took swift action to prevent any further unauthorized exposure of customer email addresses.  Within hours, AT&T disabled the mechanism that automatically populated the email address. Now, the authentication page log-in screen requires the user to enter both their email address and their password. I want to assure you that the email address and ICC-ID were the only information that was accessible. Your password, account information, the contents of your email, and any other personal information were never at risk.  The hackers never had access to AT&T communications or data networks, or your iPad.  AT&T 3G service for other mobile devices was not affected. While the attack was limited to email address and ICC-ID data, we encourage you to be alert to scams that could attempt to use this information to obtain other data or send you unwanted email. You can learn more about phishing by visiting the AT&T website. AT&T takes your privacy seriously and does not tolerate unauthorized access to its customers’ information or company websites.   We will cooperate with law enforcement in any investigation of unauthorized system access and to prosecute violators to the fullest extent of the law. AT&T acted quickly to protect your information – and we promise to keep working around the clock to keep your information safe.  Thank you very much for your understanding, and for being an AT&T customer. Sincerely, Dorothy Attwood Senior Vice President, Public Policy and Chief Privacy Officer for AT&T Technorati Tags: AT&T,iPad 3G,Email

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  • The Power to Control Power

    - by speakjava
    I'm currently working on a number of projects using embedded Java on the Raspberry Pi and Beagle Board.  These are nice and small, so don't take up much room on my desk as you can see in this picture. As you can also see I have power and network connections emerging from under my desk.  One of the (admittedly very minor) drawbacks of these systems is that they have no on/off switch.  Instead you insert or remove the power connector (USB for the RasPi, a barrel connector for the Beagle).  For the Beagle Board this can potentially be an issue; with the micro-SD card located right next to the connector it has been known for people to eject the card when trying to power off the board, which can be quite serious for the hardware. The alternative is obviously to leave the boards plugged in and then disconnect the power from the outlet.  Simple enough, but a picture of underneath my desk shows that this is not the ideal situation either. This made me think that it would be great if I could have some way of controlling a mains voltage outlet using a remote switch or, even better, from software via a USB connector.  A search revealed not much that fit my requirements, and anything that was close seemed very expensive.  Obviously the only way to solve this was to build my own.Here's my solution.  I decided my system would support both control mechanisms (remote physical switch and USB computer control) and be modular in its design for optimum flexibility.  I did a bit of searching and found a company in Hong Kong that were offering solid state relays for 99p plus shipping (£2.99, but still made the total price very reasonable).  These would handle up to 380V AC on the output side so more than capable of coping with the UK 240V supply.  The other great thing was that being solid state, the input would work with a range of 3-32V and required a very low current of 7.5mA at 12V.  For the USB control an Arduino board seemed the obvious low-cost and simple choice.  Given the current requirments of the relay, the Arduino would not require the additional power supply and could be powered just from the USB.Having secured the relays I popped down to Homebase for a couple of 13A sockets, RS for a box and an Arduino and Maplin for a toggle switch.  The circuit is pretty straightforward, as shown in the diagram (only one output is shown to make it as simple as possible).  Originally I used a 2 pole toggle switch to select the remote switch or USB control by switching the negative connections of the low voltage side.  Unfortunately, the resistance between the digital pins of the Arduino board was not high enough, so when using one of the remote switches it would turn on both of the outlets.  I changed to a 4 pole switch and isolated both positive and negative connections. IMPORTANT NOTE: If you want to follow my design, please be aware that it requires working with mains voltages.  If you are at all concerned with your ability to do this please consult a qualified electrician to help you.It was a tight fit, especially getting the Arduino in, but in the end it all worked.  The completed box is shown in the photos. The remote switch was pretty simple just requiring the squeezing of two rocker switches and a 9V battery into the small RS supplied box.  I repurposed a standard stereo cable with phono plugs to connect the switch box to the mains outlets.  I chopped off one set of plugs and wired it to the rocker switches.  The photo shows the RasPi and the Beagle board now controllable from the switch box on the desk. I've tested the Arduino side of things and this works fine.  Next I need to write some software to provide an interface for control of the outlets.  I'm thinking a JavaFX GUI would be in keeping with the total overkill style of this project.

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  • WPF zoom canvas and maintain scroll position

    - by Alex McBride
    I have a Canvas element, contained within a ScrollViewer, which I'm zooming using ScaleTransform. However, I want to be able to keep the scroll position of the viewer focused on the same part of the canvas after the zoom operation has finished. Currently when I zoom the canvas the scroll position of the viewer stays where it was and the place the user was viewing is lost. I'm still learning WPF, and I've been going backwards and forwards a bit on this, but I can't figure out a nice XAML based way to accomplish what I want. Any help in this matter would be greatly appreciated and would aid me in my learning process. Here is the kind of code I'm using... <Grid> <ScrollViewer Name="TrackScrollViewer" HorizontalScrollBarVisibility="Auto" VerticalScrollBarVisibility="Auto"> <Canvas Width="2560" Height="2560" Name="TrackCanvas"> <Canvas.LayoutTransform> <ScaleTransform ScaleX="{Binding ElementName=ZoomSlider, Path=Value}" ScaleY="{Binding ElementName=ZoomSlider, Path=Value}"/> </Canvas.LayoutTransform> <!-- Some complex geometry describing a motor racing circuit --> </Canvas> </ScrollViewer> <StackPanel Orientation="Horizontal" Margin="8" VerticalAlignment="Top" HorizontalAlignment="Left"> <Slider Name="ZoomSlider" Width="80" Minimum="0.1" Maximum="10" Value="1"/> <TextBlock Margin="4,0,0,0" VerticalAlignment="Center" Text="{Binding ElementName=ZoomSlider, Path=Value, StringFormat=F1}"/> </StackPanel> </Grid>

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  • Which Computer Organization & Architecture book is good for me?

    - by claws
    I'm always interested in learning the inner working of things. I started with C programming and then learnt Operating systems (from stallings) and then linkers & loaders and then assembly language after reading these now I want to go into little more depth. Computer Architecture. I feel that makes everything clear. As per SO archives these are the two good books: Computer Architecture: A Quantitative Approach, 4th Edition Computer Organization and Design, Fourth Edition, ~ David A. Patterson, John L. Hennessy But I've browsed through the contents of these books and found that they don't exactly meet my needs. I want to learn more about caches, Memory Management Unit , mapping b/w virtual memory & physical memory I'm no way interested in other ISAs like MIPS etc.. I'm IA32 and X86-64 fan and I want to stick to it. I'm not a hardware developer I don't want to details like circuit diagrams or How is L1, L2 & L3 caches are implemented? I want to know the parallel processing technologies like HyperThreading at the architecture level but again I don't want to design them. I liked the table of Contents of - Computer Architecture: A Quantitative Approach, 4th Edition but Quantitave Approach? Seriously?? I want to know the details of current technologies and I dont want to spend reading 200 pages of outdated old technologies ( I experienced this while learning ASM}

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  • For "draggable" div tags that are NOT nested: JQuery/JavaScript div tag “containment” approach/algor

    - by Pete Alvin
    Background: I've created an online circuit design application where .draggable() div tags are containers that contain smaller div containers and so forth. Question: For any particular div tag I need to quickly identify if it contains other div tags (that may in turn contain other div tags). -- Since the div tags are draggable, in the DOM they are NOT nested inside each other but I think are absolutely positioned. So I think that a "hit testing" approach is the only way to determine containment, unless there is some "secret" routine built-in somewhere that could help with this. I've searched JQuery and I don't see any built-in routine for this. Does anyone know of an algorithm that's quicker than O(n^2)? Seems like I have to walk the list of div tags in an outer loop (n) and have an inner loop (another n) to compare against all other div tags and do a "containment test" (position, width, height), building a list of contained div tags. That's n-squared. Then I have to build a list of all nested div tags by concatenating contained lists. So the total would be O(n^2)+n. There must be a better way?

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  • C++ linking error when linking postgresql

    - by Brent Rowswell
    When compiling my code I run into an issue as follows: io.cpp:21: undefined reference to `PQconnectdb' as well as all other instances of missing postgres function calls occurring in my code. Obviously this is a linking problem, I'm just not sure what the link issue is. I'm compiling with the following: mpiCC -c -O2 -g -Wall -Werror -I /usr/include/postgresql/ decisioning_mpi.cpp g++ -c -O2 -g -Wall -Werror -I /usr/include/postgresql/ io.cpp g++ -c -O2 -g -Wall -Werror -I /usr/include/postgresql/ calculations.cpp g++ -c -O2 -g -Wall -Werror -I /usr/include/postgresql/ rules.cpp g++ -c -O2 -g -Wall -Werror -I /usr/include/postgresql/ Instrument.cpp g++ -c -O2 -g -Wall -Werror -I /usr/include/postgresql/ Backtest_Parameter_CPO.cpp g++ -c -O2 -g -Wall -Werror -I /usr/include/postgresql/ Backtest_Trade_CPO.cpp g++ -c -O2 -g -Wall -Werror -I /usr/include/postgresql/ Data_Bar.cpp mpiCC -o decisioning_mpi -O2 -g -Wall -Werror -L/usr/lib -lm -lpq decisioning_mpi.o io.o calculations.o rules.o Instrument.o Backtest_Parameter_CPO.o Backtest_Trade_CPO.o Data_Bar.o It should be noted that this is the correct directory for libpq-fe.h and that I'm linking pq, so I'm not exactly sure why the postgres functions aren't linking correctly. I'm running Ubuntu 12.04 and installed psql (PostgreSQL) 9.1.6 from synaptic. As well I'll short circuit this, I am using #include "libpq-fe.h". Any ideas on how I can get this linking issue resolved?

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  • What Language Feature Can You Just Not Live Without?

    - by akdom
    I always miss python's built-in doc strings when working in other languages. I know this may seem odd, but it allows me to cut down significantly on excess comments while still providing a clean description of my code and any interfaces therein. What Language Feature Can You Just Not Live Without? If someone were building a new language and they asked you what one feature they absolutely must include, what would it be? This is getting kind of long, so I figured I'd do my best to summarize: Paraphrased to be language agnostic. If you know of a language which uses something mentioned, please at it in the parenthesis to the right of the feature. And if you have a better format for this list, by all means try it out (if it doesn't seem to work, I'll just roll back). Regular Expressions ~ torial (Perl) Garbage Collection ~ SaaS Developer (Python, Perl, Ruby, Java, .NET) Anonymous Functions ~ Vinko Vrsalovic (Lisp, Python) Arithmetic Operators ~ Jeremy Ross (Python, Perl, Ruby, Java, C#, Visual Basic, C, C++, Pascal, Smalltalk, etc.) Exception Handling ~ torial (Python, Java, .NET) Pass By Reference ~ Chris (Python) Unified String Format WalloWizard (C#) Generics ~ torial (Python, Java, C#) Integrated Query Equivalent to LINQ ~ Vyrotek (C#) Namespacing ~ Garry Shutler () Short Circuit Logic ~ Adam Bellaire ()

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  • Android 3.1+ USB as virtual COM port

    - by ZachMc
    I have a third party usb device, that when plugged into a Windows machine, is recognized as a serial device and assigned to the COM 4 port. I can communicate with the device just like I would with a device connected via a serial port. For instance, I can write "abc" serially to the device via the USB connection. I have been searching for a way to do a similar thing in Android. If I try the Usb Host method, and use a UsbManager to open the UsbDevice, I can get one interface, with 2 endpoints. I have tried sending control messages using the method in UsbDeviceConnection, but the method returns -1 for everything (though I don't know what I should use for the parameters of that method). Is there a way to get an OutputStream that I can write to that will send bytes to the USB device? Right now I am looking at recompiling the kernel to include a virtual COM port driver and write some native code to be able to do this. Thanks! Edit: I am using the FTDI serial to USB converter circuit. Is this compatible with Android?

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  • Tail recursion and memoization with C#

    - by Jay
    I'm writing a function that finds the full path of a directory based on a database table of entries. Each record contains a key, the directory's name, and the key of the parent directory (it's the Directory table in an MSI if you're familiar). I had an iterative solution, but it started looking a little nasty. I thought I could write an elegant tail recursive solution, but I'm not sure anymore. I'll show you my code and then explain the issues I'm facing. Dictionary<string, string> m_directoryKeyToFullPathDictionary = new Dictionary<string, string>(); ... private string ExpandDirectoryKey(Database database, string directoryKey) { // check for terminating condition string fullPath; if (m_directoryKeyToFullPathDictionary.TryGetValue(directoryKey, out fullPath)) { return fullPath; } // inductive step Record record = ExecuteQuery(database, "SELECT DefaultDir, Directory_Parent FROM Directory where Directory.Directory='{0}'", directoryKey); // null check string directoryName = record.GetString("DefaultDir"); string parentDirectoryKey = record.GetString("Directory_Parent"); return Path.Combine(ExpandDirectoryKey(database, parentDirectoryKey), directoryName); } This is how the code looked when I realized I had a problem (with some minor validation/massaging removed). I want to use memoization to short circuit whenever possible, but that requires me to make a function call to the dictionary to store the output of the recursive ExpandDirectoryKey call. I realize that I also have a Path.Combine call there, but I think that can be circumvented with a ... + Path.DirectorySeparatorChar + .... I thought about using a helper method that would memoize the directory and return the value so that I could call it like this at the end of the function above: return MemoizeHelper( m_directoryKeyToFullPathDictionary, Path.Combine(ExpandDirectoryKey(database, parentDirectoryKey)), directoryName); But I feel like that's cheating and not going to be optimized as tail recursion. Any ideas? Should I be using a completely different strategy? This doesn't need to be a super efficient algorithm at all, I'm just really curious. I'm using .NET 4.0, btw. Thanks!

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  • What is the fastest way to do division in C for 8bit MCUs?

    - by Jordan S
    I am working on the firmware for a device that uses an 8bit mcu (8051 architecture). I am using SDCC (Small Device C Compiler). I have a function that I use to set the speed of a stepper motor that my circuit is driving. The speed is set by loading a desired value into the reload register for a timer. I have a variable, MotorSpeed that is in the range of 0 to 1200 which represents pulses per second to the motor. My function to convert MotorSpeed to the correct 16bit reload value is shown below. I know that float point operations are pretty slow and I am wondering if there is a faster way of doing this... void SetSpeed() { float t = MotorSpeed; unsigned int j = 0; t = 1/t ; t = t / 0.000001; j = MaxInt - t; TMR3RL = j; // Set reload register for desired freq return; }

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  • How to define a batching routing service in WCF

    - by mattx
    I have designed a custom silverlight wcf channel that I want to leverage to selectively batch calls from the client to the server and possibly to cache on the client and short circuit calls. So far I'm just using this channel as a transport and sending the generic WCF messages that result to the WCF router service example here http://msdn.microsoft.com/en-us/magazine/cc500646.aspx?pr=blog to prototype this on the server side. So my scenario looks like this: IFooClient-MyTransportChannel-IRouterService-IFooService-Return I now need to be able to send more than one message per call through the router and carve them up and service them on the server side. Since this is just an experiment and I'm taking baby steps I will dispatch and service all the messages right away on the server side and return the batch of results. Immediately I noticed that simply making the router interface take Message[] instead of Message doesn't work due to serialization problems. I guess this makes sense. I'm not sure soap envelopes can contain other soap envelopes etc. Is there a simple way to take a collection of WCF Message objects and send them to a single method on a service where they can be split up and forwarded as appropriate? If not I'd love suggestions on how I should approach this. I want to have minimal work to do on the router service side so the goal should be to get as close to being able to "slice and forward" as possible.

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  • Progressive enhancement of anchor tags to avoid onclick="return false;"

    - by Chris Beck
    Unobtrusive JS suggests that we don't have any onclick attributes in our HTML templates. <a href="/controller/foo/1">View Foo 1</a> A most basic progressive enhancement is to convert an that anchor tag to use XHR to retrieve a DOM fragment. So, I write JS to add an event listener for a."click" then make an XHR to a.href. Alas, the browser still wants to navigate to "/controller/foo". So, I write JS to dynamically inject a.onclick = "return false;". Still unobtrusive (I guess), but now I'm paying the the cost of an extra event handler. To avoid the cost of 2 event listeners, I could shove my function call into the onclick attribute <a href="/controller/foo/1" onclick="myXHRFcn(); return false;"> But that's grodo for all sorts of reasons. To make it more interesting, I might have 100 anchor tags that I want to enhance. A better pattern is a single listener on a parent node that relies on event bubbling. That's cool, but how do I short circuit the browser from navigating to the URL without this on every anchor node? onclick="return false;" Manipulating the href is not an option. It must stay intact so the context menu options to copy or open in new page work as expected.

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